1. Field of the Invention
The present invention relates to a magnetic head assembly using for a magnetic disk apparatus or the like, to a method of manufacturing the same and to a method of wiring the same using for signal transmission between a magnetic head and external.
2. Description of the Related Art
Generally, in magnetic disk apparatus, a magnetic head assembly reads out/writes information on a magnetic disk of recording medium. A magnetic head assembly comprises a rotational arm rotating along a recording surface of a magnetic disk. On the tip of the rotational arm, a magnetic head for reading/writing information of magnetic disk is mounted.
In order to enable signal transmission between a control circuit provided on the body portion of a magnetic disk apparatus and the magnetic head mounted on the tip of the rotational arm, the control circuit and the magnetic head need to be electrically connected by use of a flexible printed circuit board or the like. A method of connecting a control circuit and a magnetic head of the related art is as follows. First, the magnetic head and a relay flexible printed circuit board (hereinafter referred to as a relay FPC board) are connected through a pattern of a conductive material formed on the rotational arm. The flexible printed circuit board connected to the control circuit (hereinafter referred to as an external side FPC board) is connected to the relay FPC board. The external side FPC board and the relay FPC board as well as the relay FPC board and the pattern are respectively connected by ultrasonic welding or solder fusion.
In such a method of connecting by ultrasonic welding or solder fusion, however, the connecting operation is complicated. This results in defects in connection. Specifically, in a method by using ultrasonic welding, gold plate covering the surfaces of the relay FPC board and the external side FPC board is peeled off.
Unexamined Patent Application Publication No. Hei 9-180380 proposes the following method. A connecting portion of the external side FPC board and a connecting portion of the relay FPC board are previously attached to the facing surfaces of two components constituting the rotational arm and the two connecting portions are connected to be sandwiched between the components in fabricating the rotational arm. The publication refers to the interposition of an adhesive having anisotropic conductivity between the connecting portions of the external side FPC board and the relay FPC board.
In the method disclosed in the above-mentioned Unexamined Patent Application Publication, the external side FPC board and the relay FPC board are connected in the rotational arm. It makes it impossible to work with the connecting condition observed. This results in poor workability. No detailed description is made for the method of connecting using an adhesive having anisotropic conductivity in the publication.
The present invention is designed to overcome the foregoing problems. It is an object of the invention to provide a magnetic head assembly with low defect in connection and good workability, and methods of manufacturing and wiring the same.
A method of wiring a magnetic head assembly according to this invention comprises the steps of: providing an arm side-wiring member, one end of which is electrically connected to the magnetic head and the other end of which has a first connecting portion, on the rotational arm; preparing an external side-wiring member, one end of which is connectable to the external circuit and the other end of which has a second connecting portion; and electrically connecting the arm side-wiring member and the external side-wiring member by overlapping the first connecting portion and the second connecting portion with a predetermined conductive adhesive member in between on the rotational arm.
In a method of wiring a magnetic head assembly according to this invention, the arm side-wiring member and the external side-wiring member are fixed, sandwiching a conductive adhesive member having anisotropic conductivity and connected to the arm side-wiring member and the external side-wiring member. The conductive adhesive member only has conductivity the direction of overlapping. This prevents conduction of each adjacent terminal even if there are a plurality of terminals in the first connecting portion of the arm side-wiring member or the second connecting portion of the external side-wiring member. The connection of the arm side-wiring member and the external side-wiring member on a predetermined exterior surface of the rotational arm facilitates the connection process.
In a method of wiring a magnetic head assembly according to this invention, desirably, a plurality of the arm side-wiring members are provided corresponding to the plurality of magnetic heads, respectively; and the first connecting portions of the plurality of arm side-wiring members and the second connecting portion of the external side-wiring member are connected in a single step in the connecting step. The rotational arm may comprise an arm tip counting the magnetic head and a rotatable arm body supporting the arm tip and the first connecting portions of the arm side-wiring members and the second connecting portion of the external side-wiring member may be overlapped in the connecting step.
Additionally, it is desirable that the connecting step comprises a step of curing of the conductive adhesive member. The conductive adhesive member may be thermosetting and heated to a temperature higher than that allowing the conductive adhesive member to be completely set in the step of curing. In this case, desirably, the conductive adhesive member is first heated to a temperature lower than that allowing the conductive adhesive member to be completely set before the step of curing. A desirable conductive adhesive member for use with this invention is an adhesive tape made of anisotropic conductive resin or a paste adhesive made of anisotropic conductive resin. Further, a flexible printed circuit board is desirable for the external side-wiring member.
Desirably, the arm side-wiring member is fabricated of the wiring pattern made of a conductive material formed on the rotational arm and the relay board for electrically connecting the wiring pattern and the external side-wiring member. In this case, the flexible printed circuit board can be used for the relay board. Further, it is desirable to include the step of overlapping and electrically connecting the relay board and the wiring pattern sandwiching a predetermined conductive adhesive member having anisotropic conductivity in the direction of overlapping.
A method of manufacturing a magnetic head assembly according to this invention comprises a step of wiring for electrically connecting the magnetic head and an external circuit, wherein the step is performed with the above-mentioned method of wiring a magnetic head assembly.
In a method of manufacturing a magnetic head assembly of the invention, it is desirable to provide the inspection terminal in the arm side-wiring member. In this case, desirable, before the above-mentioned step of wiring, the steps of: performing a predetermined inspection of the magnetic head with use of the inspection terminal of the arm side-wiring member; and removing the inspection terminal from the arm side-wiring member after the inspection are further comprised.
A magnetic head assembly of the invention comprises: a magnetic head; a rotational arm mounting the magnetic head; an arm side-wiring member, one end of which is electrically connected to the magnetic head and the other end of which has a first connecting portion, provided on the rotational arm; and an external side-wiring member, one end of which is able to electrically connected to an external circuit provided separately from the rotational arm and the other end of which has a second connecting portion, wherein the first connecting portion of the arm side-wiring member and the second connecting portion of the external side-wiring member are overlapped with a predetermined conductive adhesive member having anisotropic conductivity in between and electrically connected to each other on the rotational arm.
In a magnetic head assembly of the invention, desirably, the arm side-wiring member comprises a wiring pattern made of a conductive material formed on the rotational arm and a relay board electrically connecting the wiring pattern and the external side-wiring member, and the relay board and the wiring pattern are overlapped with a predetermined conductive adhesive member having anisotropic conductivity in between and electrically connected to each other.
Other and further objects, features and advantages of the invention will appear more fully from the following description.